.TH std::ranges::data 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ranges::data \- std::ranges::data

.SH Synopsis
   Defined in header <ranges>
   Defined in header <iterator>
   inline namespace /* unspecified */ {

       inline constexpr /* unspecified */ data = /*        \fI(since C++20)\fP
   unspecified */;                                         (customization point object)

   }
   Call signature
   template< class T >

       requires /* see below */                            \fI(since C++20)\fP
   constexpr std::remove_reference_t<

       ranges::range_reference_t<T>>* data( T&& t );

   Returns a pointer to the first element of a contiguous range.

   If T is an array type and std::remove_all_extents_t<std::remove_reference_t<T>> is
   incomplete, then the call to ranges::data is ill-formed, no diagnostic required.

   If the argument is an lvalue or ranges::enable_borrowed_range<std::remove_cv_t<T>>
   is true, a call to ranges::data is expression-equivalent to:

    1. decay-copy(t.data())
       (until C++23)
       auto(t.data())
       (since C++23), if that expression is valid and its type is a pointer to an
       object type.
    2. Otherwise, std::to_address(ranges::begin(t)), if the expression ranges::begin(t)
       is valid and its type models std::contiguous_iterator.

   In all other cases, a call to ranges::data is ill-formed, which can result in
   substitution failure when ranges::data(e) appears in the immediate context of a
   template instantiation.

.SH Notes

   If the argument is an rvalue (i.e. T is an object type) and
   ranges::enable_borrowed_range<std::remove_cv_t<T>> is false, the call to
   ranges::data is ill-formed, which also results in substitution failure.

   If ranges::data(e) is valid for an expression e, then it returns a pointer to an
   object.

   The C++20 standard requires that if the underlying data function call returns a
   prvalue, the return value is move-constructed from the materialized temporary
   object. All implementations directly return the prvalue instead. The requirement is
   corrected by the post-C++20 proposal P0849R8 to match the implementations.

.SH Example


// Run this code

 #include <cstring>
 #include <iostream>
 #include <ranges>
 #include <string>

 int main()
 {
     std::string s{"Hello world!\\n"};

     char a[20]; // storage for a C-style string
     std::strcpy(a, std::ranges::data(s));
     // [data(s), data(s) + size(s)] is guaranteed to be an NTBS

     std::cout << a;
 }

.SH Output:

 Hello world!

.SH See also

   ranges::cdata obtains a pointer to the beginning of a read-only contiguous range
   (C++20)       (customization point object)
   ranges::begin returns an iterator to the beginning of a range
   (C++20)       (customization point object)
   data          obtains the pointer to the underlying array
   \fI(C++17)\fP       \fI(function template)\fP
